Avalanche Forecast

Issued: Jan 28th, 2018 5:07PM

The alpine rating is high, the treeline rating is high, and the below treeline rating is considerable. Known problems include Storm Slabs, Deep Persistent Slabs and Cornices.

cgarritty, Avalanche Canada

South Coast Inland.

More warm, wet, and, windy weather in the forecast means that dangerous avalanche conditions will persist on Monday.

Summary

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

Sunday night: Periods of snow bringing 20-30 cm of new snow. Heavy rain below about 1100 metres, possibly 1600 metres.Monday: Continuing periods of snow bringing 10-25 cm of new snow to higher elevations. Rain below about 1600 metres. Strong to extreme southwest winds Freezing level to 2000 metres with alpine temperatures around 0.Tuesday: Mainly cloudy with isolated flurries and a trace to 3 cm of new snow. Moderate to strong southwest winds. Freezing level to 1200 metres with alpine high temperatures around -4.Wednesday: A mix of sun and cloud with isolated flurries and a trace of new snow. LIght west winds. Alpine high temperatures of -7.

Avalanche Summary

Reports from Saturday showed recently formed storm slabs reactive to skier traffic and ski cutting, producing small (Size 1, 30-35 cm deep) storm slab and loose dry releases. Poor visibility was noted to be limiting observations.On Thursday, two natural storm slab avalanches stepped-down to facets at the bottom of the snowpack and resulted in Size 3-3.5 avalanches. They occurred on north and south aspects between 2000 and 2250 m. The extended period of continuous loading of the snowpack may begin to reactivate deeply buried weak layers resulting in large and destructive avalanches running full path.

Snowpack Summary

Another 10 cm of new snow on Sunday morning brings recent storm totals to 90-120cm. Moderate to strong south winds have been redistributing each day's accumulations into dense storm slabs in lee and cross-loaded features at treeline and above.90-120cm below the surface you'll likely find a few crusts that were buried during the first few weeks of January. Due to limited observations, not much is known about the current reactivity of these layers.The lower snowpack includes the mid-December crust layer. The load of the new snow may tip the balance and reactivate this layer in isolated terrain - particularly in the north of the region where it has shown prolonged reactivity in snowpack tests.

Problems

Storm Slabs

New snow and wind will create another round of touchy storm slabs reactive to human triggers. Storm slab danger will likely increase with elevation, however rising temperatures and rain will promote loose wet avalanches at lower elevations.

Avoid avalanche terrain during periods of heavy loading from new snow and wind.The new snow may require several days to settle and stabilize.Use extra caution on slopes if the snow is moist or wet and avoid terrain traps like gullies.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 2.5

Deep Persistent Slabs

Intense loading of new snow may awaken deeply buried weak layers resulting in large, destructive avalanches.

Large triggers such as falling cornice or smaller avalanches may step-down to deeply buried crusts.Be mindful that deep instabilities are still present and have produced recent large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3.5

Cornices

Large amounts of new snow and high winds will create tender cornices sensitive to human triggers.

Falling cornices may trigger large avalanches on slopes below.Give cornices a wide berth when traveling on or below ridges

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1.5 - 2.5

Valid until: Jan 29th, 2018 2:00PM